植物激素脱落酸(ABA)是陆地植物适应水限制条件的基础。渗透压力,比如干旱,诱导被子植物ABA积累,触发生理反应,如气孔关闭。被子植物ABA信号的核心成分是可溶性ABA受体,A组蛋白磷酸酶2C型和SNF1相关蛋白激酶2(SnRK2)。ABA在非被子植物中也有各种功能,然而,这表明它在适应土地方面的作用可能不是被子植物特有的。的确,在陆地植物中,核心ABA信号成分在进化上是保守的,暗示他们在一个共同的祖先中存在。苔藓植物和藻类中ABA信号成分正在进行的功能基因组学研究的结果扩大了我们对ABA信号的进化作用的理解,即使在藻类中,基因组测序也揭示了ABA核心模块。在这次审查中,我们描述了最近在非被子植物中涉及ABA核心模块的发现,追踪ABA如何作为植物激素进化的足迹。我们还涵盖了Raf样激酶作为核心ABA模块组分SnRK2的上游调节剂的最新发现。最后,我们从进化的角度讨论了ABA信号的起源。
The plant hormone abscisic acid (ABA) is fundamental for land plant adaptation to water-limited conditions. Osmostress, such as drought, induces ABA accumulation in angiosperms, triggering physiological responses such as stomata closure. The core components of angiosperm ABA signalling are soluble ABA receptors, group A protein phosphatase type 2C and SNF1-related protein kinase2 (SnRK2). ABA also has various functions in non-angiosperms, however, suggesting that its role in adaptation to land may not have been angiosperm-specific. Indeed, among land plants, the core ABA signalling components are evolutionarily conserved, implying their presence in a common ancestor. Results of ongoing functional genomics studies of ABA signalling components in bryophytes and algae have expanded our understanding of the evolutionary role of ABA signalling, with genome sequencing uncovering the ABA core module even in algae. In this review, we describe recent discoveries involving the ABA core module in non-angiosperms, tracing the footprints of how ABA evolved as a phytohormone. We also cover the latest findings on Raf-like kinases as upstream regulators of the core ABA module component SnRK2. Finally, we discuss the origin of ABA signalling from an evolutionary perspective.